1. Field of the Disclosure
This disclosure relates to an oil quality sensor that is installed in a fryer for the purpose of indicating when the cooking oil should be changed for one or more fryer pots. This disclosure, more particularly, relates to oil quality sensor that measures an electrical property of the oil and is disposed in a filtration loop of a fryer that is external to the one or more fryer pots.
2. Description of Related Art
During use, the oil in a fryer is degraded and loses its proper cooking capacity. Specifically, the degradation is caused by oxidation, cyclic temperature increases and hydrolysis from released water. Impurities that are generated during the frying process are collectively called total polar materials (TPMs) or total polar compounds (TPCs). The TPMs are created during the deep-frying process as triglycerides break into free fatty acids and lipid molecule residues. These substances are characterized by an increased polarity and dielectric constant compared to the original triglycerides in the oil. Thus, an increased capacitance measurement of the cooking oil is indicative of an increased level of TPMs in the cooking oil.
There are several methods for testing the quality of cooking oil. Simple methods such as testing the taste, smell and color of the oil are excessively subjective, inaccurate and too time consuming. Other methods test the smoke point or viscosity of the oil. Again, while these measurements are fairly simple, they are too dependent on factors such as oil type and oil debris to be universally reliable.
Processes that include chemical or chromatographic methods are generally more comprehensive and accurate than the simpler methods. For example, currently the most widely used test tests the fatty acids that are released from glycerines during the frying process. This test depends strongly on the moisture of the frying goods. Testing for polymeric triglycerides that are formed from frying triglycerides is often time consuming and expensive.
Accordingly, there is a need for an oil quality sensor that is able to detect the level of all deterioration products or TPMs for installation in an oil return line of a fryer that uses a capacitance sensor to determine the change of dielectric constant of the cooking oil to unacceptable levels.